n-type silicon

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n-type silicon

The use of n-type and p-type silicon is a foundation concept in the design of transistors. Pure silicon is not conductive. However, it can be made conductive by adding other elements to its crystalline structure, which then become known as "n-type" or "p-type" silicon.

The interaction of n-type and p-type silicon to electric fields and to each other is used to make areas in a transistor change from conductive to non-conductive and vice versa (see crystalline semiconductor). See FET, MOSFET, bipolar transistor and doping.

N-Type (Negative)
N-type silicon is silicon that has been chemically combined (doped) with phosphorus gas to make it conductive. A silicon atom has four electrons in its outer shell and bonds tightly with four surrounding silicon atoms creating a crystal matrix with eight electrons in the outer shells. However, phosphorus has five electrons, and when combined, the fifth electron becomes a "free" electron that moves easily within the crystal when a voltage is applied. Because the charge carriers are electrons, n-type refers to a negative charge.

P-Type (Positive)
In contrast, p-type silicon is silicon doped with boron gas that turns it into a conductive material that readily accepts electrons when voltage is applied. Boron has only three electrons in its outer shell and can bond with only three of the four surrounding silicon atoms. This leaves one silicon atom with a vacant location in its outer shell, called a "hole," that readily accepts an electron. Because the charge carriers are holes, p-type silicon is said to have a positive charge.

N-Type and P-Type
This is a very conceptual illustration of the atomic structure of n-type and p-type silicon. (Image courtesy of TechBites Interactive, www.techbites.com)
References in periodicals archive ?
The ptype observations have been used to help characterize the sensitivity of various ptype algorithms to model errors (Reeves et al.
Given that the skill of NWP ptype forecasts have been characterized with mPING observations, a compelling next step is to use the mPING observations to build a new, hopefully improved, ptype algorithm.
Applying RFs in this way results in marked improvement in the ptype prediction form NWP models.
pTYPE approaches the problem differently: tandem DSCs will be developed which combine a n-type and a p-type DSC in a single p/n device.
Next, a PTYPE field is transmitted by master ECU_A, and the slave ECU_B and slave ECU_C simultaneously transmits the request ID_B and request ID_C respectively on the communication bus.
The difference with event-triggered method lies in the addition of a PTYPE field in the header.
A TE module consists of multiple leg pairs, each made of n-type and ptype TE materials, which are connected electrically in series and thermally in parallel to form a TE module.
A high-purity grade of Ptype carbon black developed by Cabot Corp.
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